a, b Co-immunoprecipitation to detect the interaction of full-length KREMEN1 (a) or ASGR1 (b) with S-ECD, NTD, RBD or S2 domains respectively. c KREMEN1, ASGR1 or ACE2 expressing HEK293E cells were incubated with different concentrations of S-ECD-hFc of SARS-CoV2 or SARS-CoV, separately, and S-ECD binding was monitored by flow cytometry to determine Kd. d Binding of NTD, RBD, or S2 domains with HEK293E cells expressing the KREMEN1 or ASGR1. e, f Co-immunoprecipitation to detect the interaction of S-ECD with truncated forms of KREMEN1 (e) or ASGR1 (f). g Binding of S-ECD with HEK293E cells expressing mouse Kremen1 or Asgr1. h, i Chimeric KREMEN1 (h) and ASGR1(i) were constructed and transfected into HEK293E cells, and S-ECD binding were measured by flow cytometry.